1995 Rockwood Regent

Trying to find out if anybody knows how to get rear air conditioner to work on my motorhome . Owners manual says you can only run 1 air conditioer @ a time & that there is a switch to change from 1 to the other . Owners manual says the switch is supposed to be on the side of the bed frame . We have looked all over the motorhome to find switch & cannot find . There is no 120volt power to the rear air conditioner now but worked when we first looked at it . We have not knowingly changed anything . Any clues would be appreciated